[3.13] gh-130163: Fix crashes related to PySys_GetObject() (GH-130503)

[serhiy-storchaka]

The use of PySys_GetObject() and _PySys_GetAttr(), which return a borrowed reference, has been replaced by using one of the following functions, which return a strong reference and distinguish a missing attribute from an error: _PySys_GetOptionalAttr(), _PySys_GetOptionalAttrString(), _PySys_GetRequiredAttr(), and _PySys_GetRequiredAttrString(). (cherry picked from commit 0ef4ffe)

• Issue: Crash when concurrently writing with print and concurrently modifying sys.stdout #130163

[miss-islington-app]

Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

[miss-islington-app]

Sorry, @serhiy-storchaka, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 7c1b76fce8c8df00da38830f72dbdde6881a33be 3.12 

[vstinner]

This change introduced reference leaks in the 3.13 branch. Example:

$ ./python -m test test_genericalias -R 3:3 (...) test_genericalias leaked [108, 108, 108] references, sum=324 (...) 

cc @encukou

[vstinner]

Example of buildbot failure, Fedora Stable (x86): https://buildbot.python.org/#/builders/1471/builds/551

Failed tests:

• test_genericalias
• test_ast
• test_pickletools
• test_typing

[serhiy-storchaka]

Indeed, there is a leak in _pickle.c caused by mistake in backporting. Should be fixed by #130568. Thank you @vstinner for noticing.

[bedevere-app]

GH-130576 is a backport of this pull request to the 3.12 branch.